You're right that it's important to break down a game mechanics into viable chunks, but when those chunks themselves are not interesting, then I start getting worried whether the enterprise itself is worthwhile.
The chunks alone without any detail usually aren't interesting. Break down Team Fortress 2, for example.
"Team A attempts to prevent Team B from completing objective" or "Team A shoot Team B".
The fun parts come from the details. Step it up to the next level:
"Team A attempts to prevent Team B from moving a bomb to the objective by giving players a choice of classes with a variety of weapons and abilities and pitting them against each other."
That sounds more like a game, despite the clinical description. Add in the fluff:
"A group of mercenaries working for the mega-corp 'Red' attempt to prevent an identical group of mercenaries (working for another mega-corp, 'Blu') from moving detonating a bomb in their base. Each of the nine mercenaries has a unique set of weapons and abilities that allow them to fulfill different roles in the team, all amidst a comedic and lightheartedly brutal war."
And that's without going into the specifics of each class (cloaking, headshots, ubercharging, sentries/teleporters/dispensers, rocketjumping, sticky traps, spychecking, airblasting, etc). Every game starts with a boring description. "Take turn, buy stuff, end turn" isn't that bad.
What is the player buying? Ships? Parts? Weapons? What differences do the ships have (size, speed, etc.)? What do the weapons do (think of the differences between bullets and projectiles in TF2: bullets are hitscan, projectiles travel over time. Both are weapons, but there's a very distinct mechanical difference between instead of just having numbers change)? Instead of upgrading from weak missile A to strong missile B, could there be guns? Lasers? Tractor beams? What are the effects of each type of weapon?
What variables are involved? Do the ships have limited power? Could a player be forced to choose between attacking without defenses (and subsequently being at the mercy of the RNG) or diverting power to their shields and increasing their odds of survival until a more opportune time?
Sorry for the rambling monologue, I'm just spitballing ideas. As a general rule, it's better to have a few simple (and very diverse) mechanics that interact with each other a lot rather than the endlessly increasing numbers that phrasing the idea as 'take turn, buy stuff, end turn' suggests. There's a lot you can do with that one starting point.
You need not limit such simplicity to video games. In reality (as in real life), it is a general rule of the universe that the simple breeds the complex. But lets not get too far in the realm of natural philosophy, and just stick to games
Consider, for example, the game of chess (a game I dearly love). The mechanics of chess are incredibly simple:
1. There is "space" (the board)
2. There is "material" (the pieces)
3. There is a winning objective (Mate the king)
We can get more specific as above:
1. There are 64 squares
2. There are 16 pieces, 6 unique, which have different ways of controlling space
3. Because each player starts with the same initial conditions, minor advances must be made toward the winning objective (control the center, win material, occupy weak squares etc.)
We can go deeper and describe how each piece moves and special moves (checks, captures, en passant, promoting pawns, castling etc.) And from there the game becomes so complex that it is still played today despite its 1500 year history.
Or take the game of Go, which is even older. There are literally only two rules:
1. You may place a stone on any of the boards intersection's
2. If stones are placed such that they surround a stone(s) of the opposing color (i.e the stones cover all intersections surrounding the stone(s)), that stone is put out of play
(there is a third rule forbidding the repetition of positions, but this need not be directly stated since it is somewhat self-evident)
And from that we have a game so incredibly complicated and universal, that it is theorized if aliens play a game, it is probably similar to Go.
The essence of innovation in game-making (in anything really), is to take the existing mechanics and mix and match them in new ways. The mechanics alone give you nothing, combination allows everything. Everything in the universe follows this rule, from the simplest elements of life to the latest tower defense game. The question is whether the masses will respond to your genius (you can be assured some minority always will, this forum is an example of that) or turn away. The problem then becomes selling the game people want to buy rather than making the game you want to play.
Ah, but a man's reach should exceed his grasp
Or what's crowd-funding for?